One of the most bizarre places in Europe is the town of Baarle-Hertog/Baarle-Nassau, a town within another town. The reason for this European oddity is that in the 12th century the lord of the region began selling off chunks of land to another duke. Eventually, centuries later, those dukedoms evolved into different countries, but the borders remained the same. This created the unique situation where patches of the same town are technically in two different countries. Weirder still, the border actually passes through buildings and houses.